diff --git a/lib/customer_plan.rb b/lib/customer_plan.rb
index 3a58df0adda342680a847eb1a911eac54f40d08d..870b5d30f9e0c93386ef42d14e97c539bf77a566 100644
--- a/lib/customer_plan.rb
+++ b/lib/customer_plan.rb
@@ -27,8 +27,8 @@ class CustomerPlan
 		@customer_id = customer_id
 		@plan = plan || OpenStruct.new
 		@expires_at = expires_at
-		@auto_top_up_amount = auto_top_up_amount
-		@monthly_overage_limit = monthly_overage_limit
+		@auto_top_up_amount = auto_top_up_amount || 0
+		@monthly_overage_limit = monthly_overage_limit || 0
 	end
 
 	def active?